ETIOLOGY - ACUTE EXUADATIVE NEPHRITIS.
Acute exudative nephritis is frequently a primary inflammation, occurring either after exposure to cold or without discoverable cause. It may complicate any one of the infections inflammations or diseases, but is especially common with scarlet fever. It is one of the forms of nephritis which are caused by pregnancy.
Acute exudative inflammation in any part of the body seems to be caused by local irritation, by the presence of irritating substances in the blood, and by changes in the circulation of the blood in the in flamed portion of the body. Pathogenic bacteria are sometimes present, sometimes absent in the inflamed tissue.
Unquestionably all the infectious diseases are often complicated with inflammations of different parts of the body. The probable causes of these are the chemical poisons produced by the growth of the pathogenic bacteria belonging to each disease. It seems also that the poison of each disease has a preference for particular por tions of the body. In rheumatism the joints and heart are regularly
inflamed; in measles, the bronchi; in scarlet fever and diphtheria the throat and the kidneys.
As regards the presence of bacteria in the kidneys themselves as exciting causes of inflammation our knowledge is uncertain.
Whether nephritis in puerperal women and after exposure to cold is clue to disturbances of circulation or to some poison in the blood is not certain.
There are marked differences in the severity of different cases of nephritis. The exudation of serum is larger in one case, the emi gration of white blood-cells in another. In one kidney the epithelial cells are contracted, in another they are swollen and degenerated. The glomeruli are much more changed in some kidneys than in others. How closely these differences in the lesions correspond to differences in the causation of the nephritis we do not know.